This invention relates to an improved process for preparing catalyst compositions for a process in which cyclohexyl hydroperoxide is decomposed to produce a mixture containing cyclohexanol and cyclohexanone. More particularly, the invention relates to an improved process for preparing stable dispersions or solutions of certain metal-ligand catalyst compositions.
Industrial processes for production of mixtures of cyclohexanol and cyclohexanone from cyclohexane are currently of considerable commercial significance, and are well described in the patent literature. In accordance with typical industrial practice, cyclohexane is oxidized, forming a reaction mixture containing cyclohexyl hydroperoxide (CHHP). The resulting CHHP is decomposed, optionally in the presence of a catalyst, to form a reaction mixture containing cyclohexanol and cyclohexanone. In the industry, such a mixture is known as a K/A (ketone/alcohol) mixture, and can be readily oxidized to produce adipic acid, which is an important reactant in processes for preparing certain condensation polymers, notably polyamides. Due to the large volumes of adipic acid consumed in these and other processes, minor improvements in processes for producing adipic acid and its precursors can provide beneficial cost advantages.
Dougherty, et al., U.S. Pat. No. 2,609,395, disclose a process for oxidation of cycloalkanes to produce cycloalkanols and cycloalkanones, wherein a cycloalkane is reacted with limited quantities of oxygen. The cycloalkane hydroperoxides thereby produced are decomposed by heating in the presence of a cycloalkane, producing cycloalkanols and cycloalkanones.
Gallo, et al., U.S. Pat. No. 2,675,407, disclose optional use of polyvalent metal catalysts in a process for oxidizing cycloalkanes. Specific catalysts disclosed include finely divided metals such as cerium, cobalt, copper, manganese and vanadium, as well as inorganic and organic salts or oxides containing such metals.
Cates, et al., U.S. Pat. No. 2,851,496, disclose a process in which cyclohexane is oxidized with molecular oxygen, optionally in the presence of a catalyst, to provide a mixture containing cyclohexanol, cyclohexanone, and CHHP. According to this process, the resulting CHHP is subsequently decomposed to K and A by heating the mixture in the presence of a bed of solid decomposition catalyst. Catalysts disclosed by this reference include solid, granular metals or metal oxides deposited upon inert supports.
Simon, et al., U.S. Pat. No. 3,093,686, disclose a process for oxidation of cyclohexane to produce mixtures of cyclohexanol and cyclohexanone, wherein oxidation is conducted in the presence of organic acid salts of cobalt, lead, manganese and chromium, which are added to a reactor as solutions in cyclohexane.
Pugi, U.S. Pat. No. 3,530,185, discloses a staged process for oxidizing cyclohexane in which a mixture of gases containing oxygen is introduced to a stream of cyclohexane at a temperature from 140.degree. C. to 200.degree. C. Optionally, a metal catalyst, e.g., cobalt in the form of a hydrocarbon-soluble compound, can be added to the cyclohexane stream.
Costantini, et al., U.S. Pat. No. 3,923,895, disclose a process for decomposing CHHP by heating a solution of CHHP and cyclohexane in the presence of a cyclohexane-soluble chromium derivative, which is added to a reactor column as a solution in cyclohexane.
Brunie, et al., U.S. Pat. No. 3,925,316, disclose a method of catalytically decomposing CHHP comprising heating a mixture of CHHP and cyclohexane in the presence of a soluble organic salt or chelated derivative of vanadium, molybdenum, or ruthenium.
Kuessner, et al., U.S. Pat. No. 3,917,708, disclose a process for oxidizing cycloalkanes in the presence of heavy metal salt oxidation catalysts. The anions of the heavy metal salts can be monoalkylphosphate, dialkyl phosphate, monoalkyl sulfate, alkylsulfonic acid, alkylphosphonate or dialkylphosphonate.
Brunie, et al., U.S. Pat. No. 3,927,105, disclose a cascade CHHP decomposition process employing soluble chromium derivatives, e.g., chromium carboxylates and chelated chromium derivatives, which are introduced, in solution, at the base of a reactor column.
Rapoport, et al., U.S. Pat. No. 3,957,876, describe a process for oxidizing cyclohexane in which a cyclohexane-soluble cobalt salt is employed as catalyst. Suitable catalysts disclosed include cobalt naphthenate, cobalt octoate, cobalt laurate, cobalt palmitate, cobalt stearate, cobalt linoleate and cobalt acetylacetonate.
Barnette, et al., U.S. Pat. No. 3,987,100, disclose a process for oxidizing cyclohexane in the presence of a binary catalyst system comprising prescribed amounts of cyclohexane-soluble chromium and cobalt salts, wherein CHHP formed during the reaction is decomposed to K and A in the presence of the binary catalyst.
Semenchenko, et al., Russ. J. Phys. Chem. 47 (5), 654 (1973) describe experiments indicating that the rate of CHHP decomposition in the presence of a cobalt stearate catalyst decreases as the reaction proceeds, presumably due to catalyst deactivation.
Catalytic decomposition of other organic hydroperoxides in the presence of certain cobalt complexes with anionic heterocyclic nitrogen-donor ligands has been reported. Hock and Kropf, J. Prakt. Chem. 9, 173 (1959) describe oxidation of cumene in the presence of phthalocyanine derivatives of seven different metals. Of these, cobalt phthalocyanine provided the highest overall conversion of cumene to oxidation products, the highest conversion of cumene to K/A mixture, and the lowest conversion to cumene hydroperoxide in the final mixture of products. Since acetophenone and 2-phenyl-2-propanol (K and A respectively) are known decomposition products of cumene hydroperoxide, it can be inferred that cobalt phthalocyanine was the most efficient catalyst for the cumene hydroperoxide decomposition reaction. Similarly, Kamiya, Kogyo Kagaku Zasshi 72(8), 1693, (1969), Chem. Abstr. 72, 11793Y, (1970) discloses that cobalt phthalocyanine exhibited greater catalytic activity than cobalt dodecanoate in the oxidation of cumene and autooxidation of ethylbenzene. In each case, the increased activity was attributed to "the decomposition of hydroperoxides".
Ochiai, Tetrahedron 20, 1819-1829 (1964) describes experiments in which cyclohexane was oxidized in the presence of cobalt, manganese and iron phthalocyanine.
Druliner, et al., U.S. Pat. No. 4,326,084, disclose an improved catalytic process for oxidizing cyclohexane to form a reaction mixture containing CHHP, and for subsequently decomposing the resulting CHHP to form a mixture containing K and A. The improvement comprises use of certain transition metal complexes of 1,3-bis(pyridylimino)isoindolines as catalysts for cyclohexane oxidation and CHHP decomposition. According to this patent, these catalysts demonstrate longer catalyst life, higher CHHP conversion to K and A, operability at lower temperatures (80.degree.-160.degree. C.), and reduced formation of insoluble metal-containing solids, relative to results obtained with certain cobalt (II) fatty acid salts, e.g., cobalt 2-ethylhexanoate. This patent discloses several methods for preparing the catalysts. One of the methods comprises mixing one to about two equivalents of a 1,3-bis(pyridylimino)isoindoline with a transition metal (II) salt, preferably a carboxylate, in a solvent such as benzene, chlorobenzene, or cyclohexane.
Robinson, et al., Inorg. Chem. 6(2), 392-394 (1967) disclose a method of preparing transition metal complexes of 1,3-bis(2-pyridylimino)isoindolines by reaction of transition metal acetate salts with 1,3-bis(2-pyridylimino)isoindolines in methanol, forming a complex exhibiting "increased solubility in organic solvents".